Developmental psychology is a subfield of psychology that researches human body, behavior, thought, feelings, social relationships and alterations that depends on age. It is a scientific approach which aims to explain growth, change and consistency though the lifespan.
Before scientific method, a lot of philosopher produced a lot of idea about development. The first philosopher who produced an idea about development is Augustine of Hippo. His assertion is ‘Original Sin’. According to Augustine, all humans are born with selfishness, stubbornness and sinfulness. Disiplined life can reduce the influence of this inborn tendency toward sinfulness. According to this perspective parents should help the children to correct immoral tendencies and they should restrain the children.
Another philosophical idea is ‘Blank Slate’ (Tabula Rasa) of John Locke. According to this idea, all humans are born with the ability to become literally anything or anyone; the differences between people can be explained by childhood experiences, environment and behavior shaping.
Jean Jacques Rousseau’s idea about development is ‘Innate Goodness’. Rousseau suggested that all humans are naturally good and seek out experiences that help them grow. Rousseau believed that nurturing and protection are the only needs of children to reach their full potential. Good care, nutrition and protection means good development; opposite conditions mean bad development for children.
Philosophy created the basic ideas about human development but in 19th century people used scientific methots to understand development. By 1930, the foundations of modern developmental psychology had been established.
The first organized studies about human development was made by Charles Darwin. Darwin and other evolutionist thought that the best way to understand human development was studying on children and they started to write down their children’s early development. Darwin’s theory of evolution is so important for developmental psychology and it is the source of many ideas in modern developmental psychology. For example, the concept of developmental stages comes from this theory.
G. Standley Hall used more objective ways to research development. He interviewed a lot of children and he conducted surveys to children. According to his theory of recapitulation, every person goes through changes in the psychic and somatic senses which follow the evolution scale of the body and mind. Hall believed that children develop best when not forced into constraints but giving evolutionary freedom to grow and develop in whichever way suits them.
Jean Piaget is the most influential scientist for developmental psychology. He and his wife writed down their children’s intellectual and language development. He researched the logical thinking development in children and he suggested that logical thinking develops in four stages between birth and adolescence. At the first stage, babies explore the environment by using their senses and motor abilities. At the second stage, children’s ability to use symbols to think and communicate develop. At the third stage, children learn logical thinking. Finally, in adolescent years, teenager learns to apply logic to both abstract and hypothetical problems. This theory of Piaget is the foundation of modern cognitive developmental psychology.
According to Paul Baltes, biological, sociocultural and individual factors are important to understand development. His view is ‘Lifespan Development’. He did not consider just childhood and adolescent; he also examined adults and olders and their changes and regressions. So, for this view 2 things are important: the first one is that development is a process that starts with insemination and end with death. So, this view parts from views which centers are bodily development. Secondly, this view suggests that development did not end with maturation or the end of grow. In adiition that, Baltes gave point to stability and alteration of behavior during lifespan. People sympathize this view because of increasing average age.
There are a lot of theories and hypothesis about development. They researched development in terms of different perspectives. For example, psychosocial development, moral development, language development, cognitive development, psychosexual development etc.
Body, D, Johnson P and Bee H. Lifespan Development. Chapter 1: Basic concepts and methods. Page:1-20